Process for purifying polluted liquids and industrial waste



Patented June 4, 1929..

sa -rs ZIOHN it. TRAVERS, F COLUMBUS, 013110, ASSIGNQR, BY DIREGT AND MESNE ASSIGN- MEETS, 1'0 THE TRAVERS PROCESS CURPORATION, 0F CQLUMB'US, UHIEO, A COR- PDRATION. OF OHIO.

PROCESS FOR PURIFYING POLLUTED No Drawing.

are colloids. As a specific example, I have found that 80% of faecal matter vigorously shaken with Water is colloidal and that about 85% of the entire oxygen demand of the solution is due to the colloidal fraction. Since the putrescible matter is present in organic Wastes in colloidal form, it may be effectively sepa-, rated from the waste when the same has an alkaline reaction and the colloids carry a negative charge, by incorporating in the organic Waste an electrolyte producing material, characterized by its ability to dissociate into positiveand negative ions, the reaction being that the positive ions, separated from the electrolyte producing material, are ad- 2 sorbed b the negative colloids, destroying their sta ility and transferring their condi tion from one of dispersion to one of suspen sion, permitting them to be readily carried down by any suitable coagulant. Several electrolyte producing materials have been found suitable for use inprocesses for-the purification of organic wastes. This process relates specifically to the employment as an electrolyte producing material, of a treating mixture, the major portion ofwhich represents a waste product in the form of precipitated sludge derived from the treatment of waste acid liquors discharged from the pickling vats of steel mills, with a reagent .com-

posed principally of an electrolyte producing material and calcium hydroxide,

I have found that .the sludge precipitated from waste acid liquors when treated with a mixture of calcium hydroxide and an electrolyte producing material having a high content of OaCO possesses qualities which render the same particularly well adapted to the treatment of organic waste liquors having a 7 Application filed October 17,

yielding. additional LIQUIDS AND INDUSTRIAL WASTE.

1927. Serial No. %26,828.

, V y I substantial content of putrescible colloidal matter. The waste acid liquors from pickling vats of steel mills of course contain substantial quantities of ltI SO and iron salts usuwhich I propose to use as an electrolyte producing material in the treatment of organic waste liquors to remove the putrescible colloidal content therefrom. a

It will be appreciated that when the Ca(OH) is added to the acidwaste the following reaction, will occur:

oa oH ,+H so.-=oaso.+2r1 o resulting in the precipitation of the CaSO,.

The addition of CaCO to the acid waste also results in the production of precipitated CaSO; since CaCO +H,SO =OaSQ,+'H CO Furthermore, some of the Ca(OH) reacts with the FeSO content of the acid waste as follows which is found in the resultant sludge.

This sludge is characterized by the fact that it contains undissolved' portions of the elecprecipitated; Ca SO, i

trolyte producing material employed in the treatment of the acidified liquors, together with iron salts and-calcium sulphate precipi-' tated from the acid steel mill waste during the treatment thereof. As specifically illustrating the characteristics of this sludge, thefollowing analysis of a sludge obtained by the treatment of steel mill acid waste with a reagent containing Ca(OH) 2 and an electrolyte producing material having a substantial content of CaCO in the proportions of substantially 1 to 4 is given. It will be appreciated that the sludge will vary somewhat, depending upon .the particular type of steel mill waste treated, and that no fixed analysis can be given. However, a sludge actually obtained showed upon analysis Per cent.

The electrolyte producing qualities of this sludge are, to a considerable degree, due to the presence therein of precipitated CaSO The extreme fineness of this precipitated CaSO increases the rate of its solution in the organic waste treated thereby increasing the rate of adsorption of the positive ions by the negative colloids in the organic waste. It is to be noted that this sludge contains a substantial quantity of iron salts which function when the solution is employed in the treatment of an organic waste, as a coagulant to carry down the colloids when the charges thereof have been neutralized by the adsorption of the positive ions released from the electrolyte.

Since some organic wastes have a decided acid reaction, and since the charge of the colloids can be best neutralized when the waste has an alkaline reaction, it will be further found desirable to employ, in the treatment of the organic waste, a quantity of hydrated lime in addition to the sludge obtained from the treatment of steel mill waste in the manner hereinbefore described.

In some instances, it will be found that the iron salts present in the sludge obtained from the steel mill waste, are insuflicient in quantity to supply the necessary coagulant for carrying down the suspended matter from the organic Waste. In such cases, there may be advantageously incorporated with the sludge, hereinbefore discussed, a suitable quantity of ferrous sulphate.

At this point, it should be noted that the iron salts present in the sludge, separated from the steel mill waste readily'take up oxygen. Accordingly these iron salts at the time of use in treating organic waste will represent iron which has been oxidized from the ferrous to the ferric state, and therefore these iron salts, when employed as a coagulant in the treatment of the organic waste, do not take up oxygen, with the result that the effluent produced in the purification of the organic waste contains a higher per cent of dissolved oxygen than would be the case if ferrous iron alone were employed to supply the coagulant. a

With respect to the incorporatlon of the electrolyte in the organic waste, it is significant that while the positive ions of the electrolyte are adsorbed b the ne atiyely charged colloids, the negative S0, or 0 1ons of the electrolyte unite with the water of the imam? solution, releasing nascent oxygen according to the following reactions 2S0, plus 2H O=2H SO, plus 20 260 plus 211 0 2H,,CO plus 20.

and

Total solids 1238 P. P. M. Total organic matter 520 .P. M. Total mineral matter 718 P. P. M. Total suspended matter 34:1 P. P. M. Total organic suspended matter 180 P. P. M. Total mineral suspended matter 161 P. P. M. Organic nitrogen 28.0 P. P. M. Albuminoid nitrogen 8.4 PP. M. Ammonia nitrogen 12. 0 P. P. M. Nitrate nitrogen 0. 0 P. P. M. Nitrite nitrogen 12 P. P. M. Dissolved oxygen 0.0 P. P. M. 24: hour biochemical oxyge demand 147.. 2 48 hour biochemical oxygen demand l 195. 6 10 day biochemical oxygen demand.; 350. 2 Hydrogen ion concentration 7. 4 Total bacteria" 6, 800,000 per C. C. B. coli 860,000 per G. C.

This sewage, was treated with a treating mlxture comprising 67.8 parts of sludge 0btained from the treating of steel mill waste,

as above described; 25 parts of hydrated lime; and 7.2 parts of ferrous sulphate. The treating mixture is addedto the polluted liquid and the liquid agitated t0 intimately incorporate the mixture in the li uid'. The constit-uents of the mixture may e varied with in comparatively Wide limits, as for example, the quantity of the sludge in the mixture may vary from 60 to 7 5 parts, the hydrated lime from 25 to 35 parts, and the ferrous sulphate from 6 to 10 parts, orif the sludge is sufiiciently rich in iron salts, no additional ferrous sulphate need be added. This treating mixture is used in an amount suflicient to give complete clarification of e the sewage. The

proper amount may be readily ascertained by noting the size of the floc, the rapidity of precipitation and the clarification of the lieuid. It may be stated that for an organic waste of the character of domestic sewage, from 3 to 7 pounds of the mixture will e found adequate to treat 1000 gallons of the sewage. It will be appreciated that the more concentrated the organic waste, the greater wide limits both as to the quantity of treating mixture necessary to efiect purification thereof. Sewage contorne ing to the above analysis, when treated with 4. pounds of the above mixture per thousand gallons of sewage in the manner alcove set forth, yielded an efiluent which showed upon analysis the following Total solids 760 FIRM. Total organic matter 102 P. P. M. Total mineral matter 658 P. P. M. Total suspended matter 5 P. P. M. Total organic suspended matter P. P. M. Total mineral suspended matter 3 P. P. M. Organic nitrogen 3.8 PjPlM. Albuminoid nitrogen ./V- .7 P. P. M. Ammonia nitrogen 11. 9 P. P. M. Nitrate nitrogen .2 P. P. M. Nitrite nitrogen 15 P. P. M. Dissolved ox gen 5.7 P. M. 24 hour bioc emical oxygen demand 4 1 RP M 48 hour biochemical oxygen demand 6 5 P. P.M 10 day biochemical oxygen demand 26.2 R]? M Hydrogen ion concentration 8.7 Total bacteria 13, 900 per C. C. B. coli 720'per C. C.

It will be appreciated that the foregoing treatment is merely illustrative of the opera tion of the process and that the process s adapted to the treatment of other organic wastes than sewage and that the treating mixture may be modified within relatively the quantity of its vanous constituents and as to the total quantity employed. The I mill or other acid waste will, however, mall instances constitute the predominating con stituent of the treating mixture.

The foregoing specific description of the operation of the process is merely illustrative and is not to be regarded in a limited sense since I contemplate within the'scope of my invention such modifications and changes as may benecessary the particular local conditions existmg at the plant where the process is to be employed.

Having thus described myinvention, what I claim is 1. A mixture for purifying polluted liquids which contain organic. matterin colloidal form, said mixture containing a substantial quantity of lime, ferrous sulphate, and a form, Ca (OH) s'uflicient to insure that t e colloids in the liquid-will carry a negative charge,-

Acontaining calcium hydroxide,

rived from the treatment of waste acid liquors sludge derived from steel.

.ing mixture per to adapt the process to sludge, the sludge content oiE the mixture he ing characterized by its having been recovered by a purifying treatment of a waste liquor having a substantial acid content and a substantial content of iron salts, thesludge containing in excess of 15% each of calcium sulphate and calcium carbonate.

2. A mixture for purifying polluted liquids which contain organic matter in colloidal form, said mixture containing a substantial quantity of lime, ferrous sulphate, and a sludge, the sludge constituent of the mixture being present therein in a quantity in excess of the quantity of either of the other constituents in the mixture, and containing in excries of 15% each of calcium sulphate and calcium carbonate. I 3. A process for treating polluted liquids containing putrescible matter in colloidal comprising incorporatin 4 therein and a substantial quantity of sludge derived from the treatment of waste acid liquors, said sludge containingin excess of 15% each of calcium carbonate,

salts.

calciumsulphate and iron 4. A process for purifying sewa ge comprising lncorporating therein a treatin mixture,

s udge deand an added coagulant, said sludge representing/in excess of 50% of the treating mixture and containin at least 15% each of calcium carbonate an calcium sulphate.

' 5. A process for purifying sewage comprising incorporating therein a treating mixture containing calcium hydroxide, sludge derived from the treatment of waste acid liquors and an added coagulant, 'said sludge representing in excess of 50% of the treating mixture and containing at least 15% each of calcium carbonate and calcium sulphate, adding said treatin mixture to the liquid in the proportions of roin 3 to 7 pounds of treat- 1000 gallons of sewage treated. x

6. The process herein described for the purification of putrescible liquid containing organic matter in colloidal form, which comprisestreating waste acid liquors from pickling vats of steel mills with Ca(OH) and CaCO .to produce a sludge containing precipitating a cute and then adding the sludge containing t e precipitating agents thus produced to the sewage.

' JOHN T. TRAVERS. 

